1. Field of the Invention
The present invention relates to a braking system for rollers, such as for rollers of inline skates, said braking system providing an anti-flattening or anti-blocking functionality and in which a hydraulic actuation system may be used.
2. Description of Related Art
Conventional force-path translation systems comprise, for example, transmissions or connecting rods. In the area of flexible force-path translation systems, there are the widely used wire cables (so-called Bowden cables) in the low cost segment, and hydraulic systems in the high cost segment.
Wire cables may be produced simply and at reasonable cost, but have various disadvantages. Actuation can occur only by pulling, but not by pushing. The transmission of force is subject to particularly high frictional losses. Branching off may be achieved only with utmost difficulties and with high losses. There is basically no possibility of control, closed-loop control or blocking.
Some of the disadvantages of wire cables are avoided by conventional hydraulic systems, however, hydraulic systems are complicated and expensive. In particular, the transmission losses are extremely small in hydraulic systems, it is possible to transmit forces both by pulling and pushing, branches are possible in a simple manner and practically without losses. Further, it is relatively easy to provide control, closed-loop control or blocking.
Conventional hydraulic systems normally comprise a large number of components. Usually, piston and cylinder assemblies are used a actuation or working elements, such assemblies requiring a large number of components wherein sealing between piston and cxcx9c1inder is necessary, and said assemblies involving a complicated structure and a relatively large size.
Therefore, solutions using hydraulics are found exclusively in the high price segment. It is, thus, an object of the present invention to provide a hydraulic system which overcomes the drawbacks of the prior art and which may be produced simply and at low cost. The hydraulic system should be maintenance-free and should operate reliably.
In the present invention, a hydraulic actuation system may be used having at least one actuation/working element being implemented such that a compressing/expanding closed volume is provided by a single piece using appropriate material, hardness and geometry such that the compression/expansion acts directionally in the direction of actuation.
Preferably, the actuation/working element comprises a port or terminal for connection with a conduit, and a main body, said main body forming a chamber for receiving hydraulic fluid, which chamber being connected with said port or terminal but otherwise being closed, said main body further comprising a generally cylindrical outer wall extending in axial direction and two generally planar end walls extending generally perpendicular to the outer wall, wherein at least one of said end walls is formed such that at least a portion thereof is axially displaced upon a change in pressure of the hydraulic fluid in the chamber.
According to a preferred embodiment of the present invention, the end wall consists of an alternating array of relatively rigid portions maintaining their shape and relatively elastic portions providing for displacement, wherein the end wall is preferably circular and consists of an alternating concentric array of at least one relatively elastic ring providing for displacement and a relatively rigid circular center portion maintaining its shape. In addition, the end wall may comprise at least one relatively rigid ring maintaining its shape and at least two relatively elastic rings providing for displacement.
For coaxial applications, the main body may comprise a through-hole defined by a generally cylindrical inner wall extending in axial direction and arranged radially interiorly with respect to the outer wall. In this case, the end wall is preferably ring-shaped and consists of an alternating concentric array of at least one relatively rigid ring maintaining its shape and at least two relatively elastic rings providing for displacement.
In another embodiment of the actuation/working element, the outer wall of the main body is formed such that a circumferential radial channel or groove is formed while maintaining a uniform thickness of material.
The actuation/working element is preferably implemented as a single piece providing a simple structure. It is preferred that the actuation/working element is made of an elastomer or of elastic thermoplastics, e. g. having a hardness of 65xc2x0-75xc2x0 Shore (A). A particularly cost-effective manufacturing method for the actuation/working element is injection molding. However, other methods of manufacturing are possible.
A particularly important part of the hydraulic actuation system is the actuation/working element which normally is connected with a conduit containing hydraulic fluid and which comprises a port or terminal for connection with said conduit, and a main body forming a chamber for receiving hydraulic fluid, which chamber being connected with said port or terminal but otherwise being closed, said main body further comprising a generally cylindrical outer wall extending in axial direction and two generally planar end walls extending generally perpendicular to the outer wall, wherein at least one of said end walls is formed such that at least a portion thereof is axially displaced upon a change in pressure of the hydraulic fluid in the chamber.
Preferably, the end wall consists of an alternating array of relatively rigid portions maintaining their shape and relatively elastic portions providing for displacement, wherein the end wall is preferably circular and consists of a concentric array of at least one relatively elastic ring providing for displacement and a relatively rigid circular center portion maintaining its shape.
The braking system according to the present invention preferably comprises at least one such actuation/working element.
In particular, the hydraulic actuation system is filled with hydraulic fluid and comprises at least one actuation element which upon actuation can cause a change in pressure of the hydraulic fluid, at least one working element which will be displaced in response to the change in pressure of the hydraulic fluid, and a connecting conduit for hydraulic fluid connecting the actuation element with the working element.
This simple hydraulic actuation system is versatile, very reliable and comparatively extremely inexpensive to manufacture.
According to a preferred embodiment of the present invention, the actuation element and the working element may be formed identically.
In a very simple way, a valve may be provided which may control or block the flow of hydraulic fluid in the connecting conduit. For example, if the connection conduit is an at least partly elastic connection tube, the valve may comprise at least one eccentric element which may be used to pinch off the connecting tube.
The above mentioned parts and possibly also other or further parts may form, or result in, a combination kit of hydraulic elements. The various elements may be combined easily. Actuation element(s) or working element(s) may be connected to a connection conduit by simply slipping on and sealing by means of a fixing ring. In a very simple manner, branched systems or systems having multiple circuits may be devised. The elements of the hydraulic element combination kit may be standardized resulting in cost-effective production and warehousing.
The hydraulic actuation system and the actuation/working element according to the present invention may find particularly advantageous application in a braking system for rollers or wheels, such as rollers or wheels for inline skates.
Conventional inline skates have either no braking feature at all or they usually have a braking block, for example made of rubber, mounted behind the last wheel of an inline skate. The conventional provisions for braking are very much insufficient and prone to accidents.
In order to brake using a conventional braking block the respective inline skate or roller skate must be tilted toward the back whereby in effect only the other skate is used for rolling which is particularly difficult for beginners and often results in accidents and injuries. Even with perfect control or mastering of the inline skates only little braking effect may be achieved using the conventional braking block, in particular on wet or uneven surfaces. Further, the braking block is exposed to high wear and must be replaced relatively often.
Furthermore, the conventional braking system consists of a large number of components which are attached to the inline skate or roller skate partly in a complicated manner such as by joints or links. Further, the braking block builds out beyond the inline skate, i.e. it protrudes towards the back, which may often be hindering. Therefore, the braking block is sometimes removed which further increases the dangers of inline skating.
In contrast, the hydraulic actuation system and the braking system of the present invention obviates all drawbacks of the prior art. It provides a technically perfect brake and actuation system by a simple cost-effective closed system. Contrary to a conventional actuation by means of wire cables, the system of the present invention has no interior friction, and branching off is easily achieved for multiple actuations or for systems having multiple circuits. The system of the present invention is free of wear and maintenance, has a long expected lifetime, provides high safety, consists of few parts only, may be retrofitted, is small, compact and easy to integrate. Due to the system being closed, there is no leaking fluid. In short, the present invention affords high tech at low cost.
Besides the application in a braking system for rollers or wheels, particularly for inline skates, the following exemplary applications for the hydraulic actuation system of the present invention are considered: actuation of chair or seat adjustment, gear change/transmission, bicycle brake, as well as every kind of actuation of lockings or remote controls/actuations.
A braking system for rollers or wheels preferably comprises a braking element for engagement with the roller or wheel, a hydraulic actuation system arranged for acting on the braking element, and an abutment for supporting the working element of the hydraulic actuation system. In accordance with a preferred embodiment of the present invention, the abutment is formed by a chassis or frame in which the rollers or wheels are rotatably mounted.
Advantageously, the braking system comprises a return spring for returning the braking element into its rest position spaced from the roller or wheel after braking engagement with the roller or wheel wherein the return spring may be formed integrally with the braking element.
Another advantageous embodiment of the braking system includes a temperature warning system which emits a warning upon excessive increase of temperature at the braking element. The warning is provided by means of at least one optical signal emitter, such as one or more light emitting diodes (LEDs), and/or an acoustic signal emitter. For example in a mobile application, the power supply for the temperature warning system may be provided by a commercially available button battery (pocket calculator battery). In a preferred embodiment, a switch is coupled with the actuation system such that the switch is actuated or switched upon actuation of the actuation system and activates the temperature warning system. Preferably, a temperature sensor is provided for sensing the heating of the braking element which sensor being arranged in close proximity to the braking element wherein the temperature sensor may be a temperature sensitive resistor, for example.
According to the present invention, a so-called anti-flattening system or anti-blocking system is provided as will be described in more detail hereinafter with reference to FIGS. 40-44. Therein, the braking system comprises a braking element for engagement with the roller or wheel, an actuation element arranged for acting on the braking element, and a viscous brake arranged between said braking element and said actuation element, said viscous brake allowing defined entrainment of the braking element by the roller or wheel to be braked.
A preferred embodiment of the viscous brake comprises a stationary housing, a follower connected to the braking element and rotatable with respect to the housing, at least one inner engagement disc, and at least one outer engagement disc, wherein the housing together with the follower defines a chamber in which said at least one inner engagement disc and said at least one outer engagement disc are arranged and which is filled with a viscous fluid, said inner engagement disc and said outer engagement disc being arranged such that they are rotated with respect to each other upon relative rotation between said housing and said follower. For example, said at least one inner engagement disc is in engagement with said follower and said at least one outer engagement disc is in engagement with said housing. Preferably, the follower is formed integrally with said braking element.
The braking element may be ring-shaped for maximum frictional engagement For improved cooling effect, the braking element may comprise a plurality of cooling fins.
Preferably, the braking system described herein will find applications in braking of rollers or wheels of inline skates.